1. Field
The present disclosure relates generally to manufacturing composite parts and, in particular, to a method and apparatus for monitoring gas generated during curing of a composite part. Still more particularly, the present disclosure relates to collecting a sample of gas generated during curing of a composite part under a vacuum.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Composite materials are used in aircraft to decrease the weight of the aircraft. This decreased weight improves performance features such as payload capacity and fuel efficiency. Further, composite materials provide longer service life for various components in an aircraft.
Composite materials may be tough, lightweight materials created by combining two or more functional components. For example, a composite material may include reinforcing fibers bound in a polymer resin matrix. The fibers may be unidirectional or may take the form of a woven cloth or fabric. The fibers and resins may be arranged and cured to form a composite part.
Using composite materials to create composite parts may allow for portions of an aircraft to be manufactured in larger pieces or sections. For example, a fuselage in an aircraft may be created in cylindrical sections and later joined to form the fuselage of the aircraft. Other examples include, without limitation, wing sections joined to form a wing or stabilizer sections joined to form a stabilizer.
In manufacturing composite parts, layers of composite material may be laid up on a tool. The layers of composite material may be comprised of fibers in sheets. These sheets may take the form of, for example, without limitation, fabrics, tape, tows, or other suitable configurations of sheets. In some cases, resin may be infused or pre-impregnated into the sheets. These types of sheets are commonly referred to as prepreg.
The different layers of prepreg may be laid up in different orientations and different numbers of layers may be used depending on the desired thickness of composite part being manufactured. These layers may be laid up by hand or using automated equipment such as a tape laminating machine or a fiber placement system.
After the different layers have been laid up on the tool, the layers may be consolidated and cured upon exposure to temperature and pressure, thus forming the final composite part. The curing may be performed in an oven. A composite part in the oven may be placed under a vacuum. For example, a composite part may be covered with a bag. A vacuum may be applied to the bag while the part is heated in the oven. The vacuum with the bag may apply pressure to the composite part.
After the composite part has been cured, the composite part may be inspected to determine whether inconsistencies are present. For example, ultrasound inspection, x-ray inspection, eddy current inspection, and other techniques may be used to determine whether inconsistencies such as delamination, debonding, or other undesired inconsistencies are present within the composite part.
If inconsistencies are identified in the composite part, an analysis may be performed to determine the cause. The result of the analysis may lead to changes in materials used, orientation of layers, heating times, temperatures, and other parameters for manufacturing the composite part.
This process, however, may be more time-consuming than desired. Depending on the inconsistencies identified, the composite part may be reworked or may need to be discarded. As a result, in some cases, the analysis may require a new composite part to be formed. Forming the new composite part may take more time and expense than desired.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.